1. Field of the Invention
The present invention relates to a semi-automatic block and tackle lacing machine, that eliminates most of the manual aspects of lacing block and tackle assemblies. It is semi-automatic as each of the blocks are manually inserted into the apparatus and the first end of a line is fed into the apparatus, which then automatically feeds the line through the blocks to complete the lacing operation.
2. Description of the Prior Art
Block and tackle assemblies are best known as devices used to obtain a mechanical advantage when moving large heavy objects. They are frequently attached to the hoist lines of cranes for vertical movement and to other devices for lateral movement. When moving heavy objects the block and tackle assembly must be large and heavy to withstand the stresses applied by the heavy loads. Threading of these large block and tackle assemblies has always been a manual task and will likely remain a manual task, since rigging such devices is usually done in the field for a series of lifts and is not a repetitive activity. Small block and tackle assemblies are a structural element of other products, particularly window balances. Window balances are attached to window sashes to reduce the effort required to raise them and also to hold them at any point between their open and closed positions by providing a counter balancing force to the weight of the window sash. A block and tackle assembly is comprised of at least two blocks and a line laced therebetween. Each block includes at least one sheave mounted therein. Currently during the manufacture of window balances, each block and tackle assembly is laced manually by attaching one end of a line to a first block, threading the free end of the line through a second block so that it passes over the sheave of the second block, threading the line back through the first block and over the corresponding sheave of that block and then returning the free end of the line toward the second block. Lacing a block and tackle assembly over a single sheave in each block provides a mechanical advantage of 2 to 1. Most window balances use a block and tackle assembly with a mechanical advantage of 4 to 1, which requires the line to be threaded over a second sheave in each block. Manual lacing of window balance assemblies is being done by hand, a slow and tedious process.
Automation of manufacturing processes increases production and reduces costs. Therefore there is a need for an apparatus that quickly laces block and tackle assemblies and is easy and safe to use.